4 DISCUSSION

Wax application has become an accepted treatment for ethnographic metals. Such coatings can leave surfaces and details muted as well as susceptible to accumulations of dust and lint. A particularly important note for ethnographic objects is that any type of coating may interfere with indigenously applied surfaces or investment material. The above case study illuminates the reversibility problems that may be experienced when objects have been coated with wax. Although the technical literature indicated that both waxes should be soluble in toluene at room temperature, the initial immersion test using this solvent produced unforeseen complications. Polyethylene wax coatings, though slightly soluble in several hydrocarbon solvents, are effectively and efficiently removed only with heated xylene.

In light of the present study, when attempting to remove wax from metal, one should be cognizant of the different components in blends of commercial preparations, and one should also consider that the apparent solubility of any one wax may vary according to the manner in which the solvent is applied. Pure microcrystalline waxes (e.g., Cosmolloid 80H) are available and may be preferable to the use of wax blends. Most important, ethnographic conservators should carefully weigh the necessity of applying wax coatings in museum environments where objects can be handled appropriately, as well as vitrined to provide protection; whenever possible, noninterventive alternatives to waxing should be sought.

ACKNOWLEDGEMENTS

The author thanks Walter Hopwood of the Conservation Analytical Laboratory, Smithsonian Institution, for FTIR analysis and interpretation of wax samples. Photographs and their color printing for this article were made possible by the National Museum of African Art.